Lotus Domino SMTP server 4.63 through 5.08 allows remote attackers to cause a denial of service (CPU consumption) by forging an email message with the sender as bounce@[127.0.0.1] (localhost), which causes Domino to enter a mail loop.
https://exchange.xforce.ibmcloud.com/vulnerabilities/7012
http://www.securityfocus.com/bid/3212